Social exclusion increases paranoia and reduces self and other learning flexibility in adolescents

Background. Enduring mental health conditions typically begin in adolescence. Social adversity (e.g., discrimination, bullying, trauma) may disrupt the development of healthy social learning processes and self and other beliefs. We tested the impact of prior social adversity and current social exclusion on paranoia, self and other beliefs and latent social learning processes in UK adolescents (15-17 years, n=502), using pre-registered hypotheses (AsPredicted #154322), causal Bayesian models, and exploratory analyses. Study Design. An experimental design tested (a) whether social exclusion interacted with prior social adversity to increase paranoia, (b) whether this occurred due to activating negative self and other beliefs, and (c) whether this was moderated by cognitive flexibility (i.e., moderated-mediation). Cognitive flexibility, alongside computational processes of social information generalisation, were assessed using The Intentions Game (Barnby et al., 2024). Study Results. Social exclusion triggered paranoia, which was intensified by prior social adversity, and substantially reduced latent belief flexibility about the self and others, inhibiting learning and subduing other-to-self generalisation (social contagion). Negative self and other beliefs were a mechanism through which social adversities lead to paranoia in the context of exclusion. Prior exposure to discrimination amplified state paranoia irrespective of inclusion/exclusion. Conclusion. Social adversity enhances susceptibility to paranoia following a social exclusion manipulation, in part due to activating negative self and other beliefs. Failure to detect pro-sociality in others, impacted by the rigidly with which negative self and other beliefs are held, as well as by discrimination in particular, likely exacerbates and maintains paranoia. Findings directly inform likely profitable intervention targets.